Endoscopic surgery commonly requires manual manipulation of surgical instruments that are introduced into a surgical site within a patient through elongated cannulas containing one or more interior lumens of slender cross section. Endoscopic surgery to harvest a vessel such as the saphenous vein or the radial artery usually involves an elongated cannula that is advanced along the course of the vein from an initial incision to form an anatomical space about the vein as connective tissue is dissected away from the vein.
Lateral branch vessels of the saphenous vein can be conveniently isolated and ligated within the anatomical space under endoscopic visualization using surgical scissors that can be positioned and manipulated through the elongated cannula. Such surgical procedures are commonly employed in the preparation of the saphenous vein for removal from within the anatomical space for use, for example, as a shunting or graft vessel in coronary bypass surgery.
Surgical scissors that are used to transect vessels within the confines of limited anatomical space formed along the course of the saphenous vein commonly incorporate electrodes on or near the tissue-shearing blades. Scissors of this type are suitable for monopolar or bipolar electrocauterization of tissue prior to transection of, for example, lateral side branches of the saphenous vein to be harvested. However, placement of the electrodes in relation to the tissue-shearing edges of the scissor blades may inhibit proper operation of the scissor blades to shear tissue and may inhibit thorough electrocauterization of a side branch vessel as the scissor blades close during transection of the vessel.
Additionally, the scissor blades are conventionally rotated about a common pivot axis at the distal end of an elongated body using actuating levers within confined dimensions to preserve the diminutive sectional area of the scissors suitable for passage through a lumen of an elongated cannula. The associated linkage to a manual actuator at the proximal end of the elongated body commonly establishes little mechanical advantage sufficient for remotely shearing tissue under control of the proximal actuator, with resultant jamming of the scissor blades or other impediments to orderly surgical procedures. Additionally, repeated opening and closing of the scissor blades is a tedious procedure required to slice tissue along an extended path.
Subcutaneous tissue-dissecting procedures are commonly performed under visualization through an endoscope that is positioned within a cannula and that is protected from directly contacting the tissue by a tapered transparent tip that performs the dissection as the assembly is advanced through tissue. The dissected tissue may also be dilated by insufflating the anatomical space formed in the dissected tissue using gas under pressure that is supplied to the dissected anatomical space, usually through an access port located at the initial cutaneous incision where tissue dissection begins. However, visualization through the transparent tip of the tissue being dissected is commonly obscured by tissue and bodily fluids that contact the tip. In addition, insufflating an anatomical space via gas introduced under pressure through the access port becomes more problematic as the anatomical space is extended remotely from the access port and the dissected tissue surrounds the dissecting instrument. It would be desirable to overcome remote tissue-cutting difficulties, and to provide reliable visualization through a transparent tip during tissue dissection to form an anatomical space in tissue while under insufflation.